Battleground states are seeing a drop in the number of likely voters planning to vote by mail, according to a poll released Wednesday.
A CNBC/Change Research poll determined that 33 percent of likely battleground state voters said they will vote by mail in the November election.
In the last poll conducted two weeks ago, 38 percent of battleground voters, from Arizona, Florida, Michigan, North Carolina, Pennsylvania and Wisconsin, intended to vote by mail.
The change in plans for battleground state voters comes after reports of the U.S. Postal Service instituting changes that have delayed mail, including the removal of mail sorting machines and mailboxes.
The largest shift came among Democratic voters; 57 percent of Democrats in the battleground states said they intend to vote by mail in the new poll, compared to 64 percent two weeks ago.
Nationally, 33 percent of all voters said they would vote for mail compared to 36 percent two weeks ago. Fifty-one percent of Democrats nationally said they plan to vote by mail, a drop of 11 percentage points.
CNBC and Change Research surveyed a total of 4,904 likely voters across battleground states, with 344 in Arizona, 1,262 in Florida, 809 in Michigan, 560 in North Carolina, 984 in Pennsylvania and 925 in Wisconsin. The poll was conducted between Aug. 21 and 23 and had a margin of error of 1.4 percentage points.
A total of 2,362 likely voters contributed to the national survey between Aug. 21 and 23. The margin of error was 2.02 percentage points.